1. Technical Field
The present invention relates to a method for designing an eyeglass lens in accordance with a visualizing action of each person and a method for manufacturing the eyeglass lens.
2. Related Art
Each person follows his/her own way when looking at an object. For example, when looking sideways, upward, or downward, a person rotates the head or the eyes (such an action will hereinafter be referred to as a visualizing action). The angle of rotation of the head or the eyes is specific to each person, and a variety of methods for designing an eyeglass lens in accordance with such a visualizing action of each person have been proposed. For example, the actual angle of rotation of the head or the eyes is measured when a person under test looks at an object, and a lens is then designed in accordance with the result of the measurement (see JP-T-2003-523244, the term “JP-T” as used herein means a published Japanese translation of a PCT patent application, JP-T-2007-536043, JP-A-2007-241276, JP-T-2008-521027, JP-A-2008-249828, JP-T-2008-511033, and JP-T-2008-541142).
On the other hand, a progressive addition lens is an aspheric lens including two refracting regions having different refracting power and a progressive region (intermediate region) which is located between the refracting regions and where the refracting power (dioptric power) progressively changes. In the thus configured progressive addition lens, aberrations present on both sides of the intermediate region limit the field of view. Further, a difference in magnification between the two refracting regions distorts an image, which leads to a phenomenon called “wobbling” in which an image appears to wobble when a person who wears progressive addition lenses moves the head.
In JP-T-2003-523244, JP-T-2007-536043, JP-A-2007-241276, JP-T-2008-521027, JP-A-2008-249828, JP-T-2008-511033, and JP-T-2008-541142, an eyeglass lens is designed in accordance with the actual angle of rotation of the head or the eyes (visualizing action), but no consideration is given to the balance between the size of the field of view of a progressive addition lens and the wobbling/distortion present therein. Further, no consideration is given to the change in visualizing action due to added aberrations and wobbling. Since the tolerance to aberrations and the tolerance to wobbling differ from person to person, an optimal lens for each wearer can be achieved by designing a progressive addition lens in accordance with the tolerance characteristics of the wearer.